Improvement in slide-valves for steam-engines



ITE STATES WILLIAM JosLIN, oE CLEVELAND, orIIo.

IMPROVEMENT IN SLIDE-VALVES FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 12.294, dated April 12, 1864..

To LZZ whom z't may concern..-

Be it known that I, WILLIAM JosLIN, of Cleveland, in the county of Cuyahoga and State oi' Ohio, have invented a new and useful Improvement in the Slide-Valve for Steam- Engines; and'l do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon.

The nature of my invention consists in so constructing the slide-valve in steam-engines as to relieve it of the steam-pressure which the common slide-valves are subject to.

Figure l is a sectional side elevation taken through the center of the cylinder and slidevalve. Fig. 2 is a top view with the valve and valve-box removed, showing` valve-seat, steamways, and exhaust or escape port. Fig. 3 is anend view with the end ot' valve-box removed, showing end of slide-valve. Fig. 4 is a top view of the slide-valve.

The construction of valve-motion, piston, 86o., in my engine is the same as common engines. It is therefore not necessary to describe those paris, as they are understood by engine-makers.

Ain Fig. 1 is the steamentrance.

B is the common slide-valve, very much elongated, and boxed on the sides and ends similar to the common valve when a cutoff valve is made to work on the top ot' the slidevalve, with this exception that I provide my valve with a flexible diaphragm or cover, which will be explained hereinafter.

C and C2 are steamways leading from the slide-valve into the cylinder.

D is the exhaust or escape port, elongated to correspond with the elongation of the slidevalve.

a and a2 is the top or cover of slide-valve box. b and b2 are the ends of the same.

g and g2 in Fig. 3 are the sides of the slidevalve box, all being fastened to the valveseatjj, Fig. 1.

E and E2 in Figs. 1, 3, and 4 is a slidingplate, with an opening through which the steam passes from the steam-entrance A in Fig. l to the cylinder.

The opening s s in Fig. 1,8 s in Fig. 3, shown by dotted lines, and s s s s in Fig. 4, is for the passage of steam, with an area equal to the steamways C and G2 in Fig. l and U and C2 in Fig. 2-thatis if the areas 'of C and C2 in Fig. 2 contains ten square inches each, then the area of the steam-passage in the slidingplate E and E2 will contain twenty square inches, which is equal to the two steamways C and G2, the object of which will be hereinafter explained.

The sliding plate E and E2 in Fig. 1 is made to work steam-tight under the slidevalve box-cover a and a2.

h h in Fig. 3 and h 7L in Fig.. 4 are sides fastened firmly to the sides of the slide-valve B, as shown by dotted lines in Figs. 3 and 4, projecting some above the slide-valve B.

d d in Fig. 1 and d d in Fig. 4 are the ends of the boxing fastened to the slide-valve B.

F and F2 in Fig. l and F and F2, shown by dotted lines in Fig. 4, are stearnways between the slide-valve B and ends of boxing d d in Fig. l and d d in Fig. 4.

G and G2 in Fig. l, G and G2 in Fig. 3, and G and G2 in Fig. 4 is a ilexible diaphragm or cover (above mentioned) fastened steam-tight upon the top of the slide-valve boxing d d and h h in Fig. 4. It is also fastened steamtight to the under side of the sliding plate E and E2, as shown in Figs. 1, 3, and 4. The flexible diaphragm or cover has an opening the same as the sliding plate E andEd, through which the steam passes.

The object of the opening being equal, as above mentioned, is to relieve the slidevalve of tbestearn-pressure which the common slidevalve is subject to. lf the common slidevalve has steam and escape openings equal to forty square inches area, and steam-pressure equal to one hundred pounds to the square inch, the pressure will be equal to forty hundred pounds upon the common slide-valve during that portion of its travel in which the outside lap of the slide-valve exceeds the steamways, and thirty hundred pounds during the remainder of its travel-thatis, if the escape port is equal to both steamways, which is often the case, and if a cut-off valve is used upon the top of the common slide-valve, (which is quite common,) it then has fort-y hundred pounds steam-pressure during that portion of the stroke which the steam is out oli'. With this common arrangement a large portion of the steam-power is used in moving the slidevalve. With my invention I save this power l st by pressing the common slide-valve upon its seat.

My new slide-valve being` constructed, as above described,with the opening ofthe steamentrance through the sliding plate and valveopenings being equal, it relieves the slide-valve of the steam-pressure. It will be readily seen if thesteam-openings s s, Fig. l, are stopped steam-tight, and thel openingsF-and F2, Fig. 1, in thebottom of the slide-valve are also stopped steam-tight, and steam allowed to enter through a small pipe, it would press down upon the valve B and on the sides h h and ends d d, and upon the diaphragm Vand sliding plate, (the openings in the sliding plate being sloped,) the valve thus arranged would have no pressure upon anything it might be placed, except its own weight, while the pressure inside might be very great. Now, if the valve is placed between two surfaces, and working steamtight, one under the valve and the other ou the top of the sliding plate, the two sur .faces so fastened together as not to be pressed away from each other; now if the steamways F and F2 are opened, the pressure would then come upon the bottom surface and press the valve up against the upper surface. If the area E and E2 is equal to twenty square inches, andthe pressure of steam is equal to one hundred pounds to the square inch, the pressure up against the upper surface will be equal to twenty hundred pounds, which would cause the slide-valve to move very hard. Now, if the stoppage is taken from the steam-openings s s, area being equal to the areas of the steamways F and F2, the pressure of twenty hundred pounds will then come against the upper surface, and the valve will move quite free. 1f an opening is made in the upper surface equal to the opening in the sliding plate, the pressure will then be transferred from the upper surface to the boiler, the slide-valve would continue to move with the same freedom as before. lf openings are made in the lower surface equal to those in the bottom of the slide-valve, the pressure upon the lower surface would then be transferred to the cylinder, the slide-valve would still continue to move with the same freedom, because the steam has no tendency to press the slidevalve down upon the lower surface or up against the upper surface. If the openings vopenings in the upper or lower surface exceed the openings in the valve. 1f the opening in the upper surface exceeds the opening in the valve and lower surface, then the pressure down will be equal to the excess of opening in the upper surface, and the reverse will take place if the opening in the lower surface exceeds those in the valve and upper surface,

less the weight of the valve thus the steampressure may be changed. This is the principle upon which my new slide-valve works. The diaphragm G and G, Figs'. l, 3, and 4, being flexible, causes the sliding plate E and E2 to move steam-tight against the cover a and a2. The tendency of the steam to work through between the sliding pla-te E and E2 and the valve-box cover a and a2 is nearly equal to the pressure of the sliding plate E and E2 against the cover a, and a2. This allows the valve to move quite free and steamtight at the same time. The same effect would take place if the flexible diaphragm was attached to the valve-box cover a and a2, and an inflexible cover attached to the slide-valve boxing d d and h h, Fig. 4, with the same sized steam-openings as the sliding plate E and E2, Fig. 4. By relieving the slide-valve of the steam-pressure I am enabled to make the steamways leading from the slide-valve to the cylinder near the ends of the cylinder, thereby allowing me to extend the exhaustway through the ent-ire space between the steamway-bridges, thus allowing an exhaust more free than common engines.

What I claim as my invention, and wish to secure by Letters Patent, is

The diaphragm G Gr2 and plate E E2, in combination with the valve B, as above described.

WM. J OSLIN.

Witnesses:

S. BALKWILL, L. D. FLANDERS. 

